In a rapid increase of data traffic recently typified by Internet, a transmission capacity in communication networks has advanced in great capacity. This great capacity has been realized by converting a transmission signal to be an electric signal to an optical signal with use of a time-division multiplex technique and a light wavelength multiplex technique. A transmission device responded to ten gigabits per second for one channel has been turned into practical use, and a wavelength multiplexing transmission device of a point-to-point type capable of transmitting in a long distance over several hundreds kilometers by using an optical amplifier, a regenerative repeater, etc., has also been turned into practical use by multiplexing several to several tens of channels per one fiber in wavelength to one optical fiber.
For a purpose of responding to a demand increase of the transmission capacity, a more economically purposed request, and a diversity of services in the future, a ring optical network in which communication nodes are connected in a ring shape, has been studied. In the optical transmission system for use in the ring optical network, a device so called an optical add-drop multiplexer (hereinafter, referred to as OADM) is used. In such optical network, an operation of network monitoring control system, which unifies to remotely manage the node devices, is made simplified, and a monitor control unit in each of the node devices is mutually communicated with each other. In consequence, an easiness of path management from a start to an end of the line so-called end-to-end has been realized, and a speeding-up for a path setting has also been realized. Further, by using an advanced optical transmission technique, it has been considered that an entire network can be realized economically by configuring that the optical signal, without performing an electric-optic conversion, passes through the node. It is normal that a one-to-one bidirectional communication is performed in the optical transmission system for use in the optical network.
In contrast, a video delivery has been discussed as an aspect of the above-mentioned diversity of services. In the video delivery, there is a possibility to realize the video delivery from an economical standpoint, compared with a method of transmitting the electric signal with use of a router, by receiving the optical signal transmitted from an arbitrary node at the plurality of nodes. In an IP (Internet Protocol) transmission method used in the router, the bidirectional communication is performed between a transmission source and a receiving destination of data, for a purpose of controlling that whether a node performs a multicast reception, when performing a one-to-N communication (multicast communication). In accordance with this, it is required to realize the one-to-N bidirectional communication even when replacing the multicast network using the router with the optical ring network.
JP-A-2005-236402 (patent document 1) discloses an example where the one-to-N communication is performed by using the optical signal, which is not an existing one-to-one communication. In the patent document 1, a downstream direction uses a drop and continue function, and an upstream direction uses the time-sharing communication system. In this way, the bidirectional communication between the transmission source node and receiving destination node is realized for the multicast data.